Sheet feeding or delivering – Feeding and delivering – Sensor located at the delivering and controls the feeding
Reexamination Certificate
2000-05-31
2002-07-16
Bollinger, David H. (Department: 3651)
Sheet feeding or delivering
Feeding and delivering
Sensor located at the delivering and controls the feeding
Reexamination Certificate
active
06419220
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method of operating a sheet-processing machine, having a sheet-pile station, a sheet conveyor for feeding the sheets to the pile station and for releasing them thereat during operation, the sheet conveyor defining an upper limit of a space extending beneath the sheet conveyor in the pile station and having a magnitude depending upon the operating condition of the machine, and a drive operatively connected to the sheet conveyor.
In sheet-processing printing machines such as are sold, for example, by the Heidelberger Druckmaschinen A.G., a German corporation of Heidelberg, Germany under the model designation SM
102
, the processed sheets form, in a sheet-pile station, sheet piles which are deposited on a lifting platform, vertically adjustable by a lifting mechanism and, in one of the possible pile-formation operating modes, rest in each case on a pile base, generally in the form of a pallet, that has been deposited on the lifting platform. Before the start of a respective print job, the lifting platform is adjusted by the lifting mechanism to such a raised position that the upper side of the yet empty pile base is located at a production level. A sheet conveyor receives the processed sheets from a last processing station of the printing machine, guides them to a level located a drop distance above the production level, over the pile base adjusted to the production level, and releases them for braking by a sheet-braking system and for subsequent pile formation. In the course of the pile formation, the lifting mechanism lowers the lifting platform automatically in a stepwise manner to the same extent as the height of the pile increases, with the result that the sheets sequentially following one another in production printing cover an essentially constant drop distance between the sheet conveyor and the production level, which is essentially maintained by the stepwise lowering of the lifting platform.
In addition to the automatic lowering of the lifting platform, a motor which actuates the lifting mechanism can also be activated manually to raise and lower the lifting platform. In particular, it is also possible for the lifting platform to be lowered completely without having a sheet pile set down thereon, thereby producing, between the lifting platform and the sheet conveyor, a clearance space that is of such a magnitude that, in particular, an operator can gain access thereto. Only when the sheet conveyor is at a standstill is this not problematic, and is even desirable inasmuch as it allows access to the clearance space in order to perform, for example, adjustments to the sheet-braking system so that braking rollers or braking belts forming the system are adapted manually to the format of the processed sheets and are adjustable, if necessary or desirable, to print-free areas of sheets printed on both sides, or in order for sheet supports provided, for example, in the form of so-called tail or nosewheels to be positioned as the conditions require.
Before a subsequent startup of the printing machine and, in particular, the sheet conveyor, an acoustic warning signal is then given in conventional printing machines in order to alert the operator working in the clearance space to leave the space and thus avert any risks posed by the sheet conveyor, which then revolves above the clearance space.
This operator-protection measure, however, also requires the operator to be vigilant and, in particular, to comply with the request, which in this case goes hand-in-hand with the latter to leave the clearance space.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention is to provide a method of operating a sheet-processing machine wherein the safety risk for operators working in the region of a delivery thereof during the operation is reduced.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method of operating a sheet-processing machine having a sheet-pile station, a sheet conveyor for feeding sheets to the sheet-pile station and for releasing the sheets thereat during operation, the sheet conveyor defining therebeneath a clearance space extending downwardly with a magnitude depending upon the operating state of the machine, and a drive operatively connected to the sheet conveyor, which comprises detecting extents of the clearance space in a vertical direction which exceed predeterminable values, and, after the drive has been stopped, forcibly keeping the drive stopped for as long as the vertical extent of the clearance exceeds a predetermined value.
In accordance with another mode, the method invention comprises forcibly stopping the drive after a prior startup thereof, if the extent of the clearance space exceeds a predetermined value.
In accordance with a further mode, the method invention comprises, after a prior startup of the drive, for an extent of the clearance space beyond a predetermined value, forcibly feeding to the sheet-pile station only those sheets which were on the way for sheet processing, and then forcibly stopping the drive.
In accordance with an added mode, the method invention comprises, during the feeding of those sheets to the sheet-pile station, which were on the way to sheet processing, preventing the extent of the clearance space from being increased in size.
In accordance with an additional mode, the method invention comprises introducing into the clearance space a divider that is bringable into and removable out of the clearance space, the extent of the clearance space being limited to a predetermined value.
In accordance with a concomitant aspect of the invention, there is provided a method of operating a sheet-processing machine having a sheet-pile station, a sheet conveyor for feeding sheets to the sheet-pile station and for releasing the sheets thereat during operation, the sheet conveyor defining therebeneath a clearance space extending downwardly with a magnitude depending upon the operating state of the machine, and a drive operatively connected to the sheet conveyor, which comprises detecting extents of the clearance space in a vertical direction, which exceed predeterminable values, and forcibly reducing to a predetermined value an extent of the clearance that exceeds a predetermined value.
Thus, in order to achieve the object of the invention, a sheet-processing machine, in particular a printing machine, having a pile station, a sheet conveyor by which the sheets can be fed to the pile station, a clearance space extending beneath the sheet conveyor and being of a magnitude which depends upon the operating condition of the machine, and a drive that is operatively connected to the sheet conveyor, is operated, in one operating mode, so that vertical extents of the clearance space which exceed predeterminable values are detected and, after stoppage of the drive, the latter is forcibly kept stopped for as long as the vertical extent of the clearance exceeds a predetermined value, while, in another operating mode, vertical extents of the clearance space which likewise exceed predeterminable values are detected, and an extent of the clearance which exceeds a predetermined value is forcibly reduced to a predetermined value.
It is frequently the case with sheet-processing printing machines that the at least one processing station of the latter, a feeder, which charges or feeds the processing station with the sheets, and the sheet conveyor of a delivery, the sheet conveyor transporting the sheets to the pile station, are in operative connection with one and the same drive, namely the main drive of the printing machine. A printing machine that is constructed in this manner and is equipped for implementing the method according to the invention thus cannot be operated if the vertical extent of the clearance beneath the sheet conveyor exceeds a predetermined value.
A preferred value of an acceptable vertical extent for startup of the printing machine is, in particular, in the order of magnitude of the dropping
Bollinger David H.
Bower Kenneth W
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Mayback Gregory L.
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